Exemplary embodiments of this disclosure relates to emergency evacuation equipment for an aircraft, and in particular to an inflation device for inflating an inflatable aircraft evacuation slide or other inflatable device.
The requirement for reliably evacuating airline passengers in the event of emergency is well-known. Emergencies at take-off and landing often demand swift removal of the passengers from the aircraft because of the potential of injuries from fire, explosion, or sinking in water. A conventional method of quickly evacuating a large number of passengers from an aircraft is to provide multiple emergency exits, each of which is equipped with an inflatable evacuation slide.
Typical emergency evacuation slide systems comprise an inflatable evacuation slide that is stored in a folded, uninflated state together with a source of inflation gas. The source of inflation gas typically comprises a gas generator, stored compressed gas, or a combination thereof. Pyrotechnic gas generators have an advantage in that they are small, lightweight, and produce a high volume of gas, however, the high temperature gas produced by a gas generator alone can cause numerous problems including sagging of the evacuation slide as the inflation gas cools and, in some cases melting or scorching of the fabric out of which the inflation slide is fabricated. Use of stored compressed gas by itself, although simple, implicates a weight penalty that must be paid for carrying a pressure vessel having sufficient capacity (in terms of volume and pressure) to inflate the evacuation slide over the wide operational temperature range specified for such slides. Additionally, where only a compressed gas is used to inflate the evacuation slide, a large drop in temperature occurs as the gases expand, often causing ice to form, which can block the flow of gas.
Modern evacuation slide inflation systems typically comprise a pressure vessel containing a stored pressurized gas, either alone or in combination with a pyrotechnic gas generator, used to supply the source gas for inflation of the emergency evacuation slide. The gas source is connected to a system having a one or more upstream high pressure flow valves and a downstream pressure regulating valve. The position of a metering element of the pressure regulating valve is influenced by both a biasing force and the pressure of the incoming flow. Because downstream pressure variation does not affect the position of the metering element, the metering element is not form a fluid tight seal when closed. Further, conventional systems may be susceptible to failures of a mechanical trigger or of the pressure regulating valve, which may result in a high pressure flow being provided to the inflatable slide.